Work roll with dulled surface having geometrically patterned uneven dulled sections for temper rolling

Abstract

A work roll has a regularly and geometrically patterned uneven dulled section on the roll surface. Eavh uneven dulled section is composed of a crest and concavity and is of crater-like configuration. In order to obtain good performance in temper rolling, the crest is in a form of an annular ring extending around the edge of the concavity. According to the invention, pattern of arrangement of the uneven dulled sections is determined in relation to the diameter of the ring-shaped crests of the uneven dulled section so as to obtain optimum performance in producing good quality, exhibiting substantially high image clarify as coated by paint, enamel or so forth.

What is claimed is: 
     
       1. A work roll for temper rolling a metal sheet comprising; a peripheral surface formed with a plurality of uneven sections in a spaced apart relationship to each other, each uneven section being constituted of a depression and an annular ring shaped projection surrounding said depression, said uneven sections being arranged to have a ratio between a center-to-center distance between adjacent uneven sections and the external dimension of the uneven section in a range of 0.85 to 1.7, and a difference between the center-to-center distance and the external size smaller than 280 μm.   
     
     
       2. A work roll as set forth in claim 1, wherein at least said projection has a hardened surface layer. 
     
     
       3. A work roll as set forth in claim 1, wherein the surface portion of said work roll at said uneven section is constituted with a plurality of different composition layers, which includes a first outermost layer of martensite, a second layer next to said first layer containing martensite and ε (epsilon) carbide, and a third layer containing martensite and carbide. 
     
     
       4. A work roll as set forth in claim 3, wherein said first layer is in a thickness range of 5 to 30 μm, said second layer is in a thickness range of 5 to 30 μm, and said third layer is in a thickness range of 5 to 30 μm. 
     
     
       5. A work roll as set forth in claim 4, wherein said first layer also contains austenite. 
     
     
       6. A work roll as set forth in claim 5, wherein said surface portion at said uneven section has a surface coat layer over said first layer. 
     
     
       7. A work roll as set forth in claim 6, wherein said surface coat layer is formed by plating. 
     
     
       8. A work roll as set forth in claim 7, wherein said plated surface coat layer is composed of chromium. 
     
     
       9. A work roll as set forth in claim 1, wherein said work roll has a contact area constructed to actually contact a back-up roll during a temper rolling operation, on which contact area, a pressure lower than 1000 Kgf/mm 2  is exerted. 
     
     
       10. A work roll as set forth in claim 9, wherein at least said projection has a hardened surface layer. 
     
     
       11. A work roll as set forth in claim 9, wherein a surface portion of said work roll comprises a plurality of different composition layers, which includes a first outermost layer comprising a composition of martensite, a second layer next to said first layer containing martensite and ε (epsilon) carbide, and a third layer containing martensite and carbide. 
     
     
       12. A work roll as set forth in claim 11, wherein said first layer is in a thickness range of 5 to 30 μm, said second layer is in a thickness range of 5 to 30 μm, and said third layer is in a thickness range of 5 to 30 μm. 
     
     
       13. A work roll as set forth in claim 12, wherein said first layer also contains a composition of austenite. 
     
     
       14. A work roll as set forth in claim 13, wherein said surface portion at said uneven section has a surface coat layer over said first layer. 
     
     
       15. A work roll as set forth in claim 14, wherein said surface coat layer is formed by plating. 
     
     
       16. A work roll as set forth in claim 15, wherein said plated surface coat layer is composed of chromium.